Steering mechanism



Sept. 8, 1936.

w. A. EATON STEERING MECHANISM Filed Jun 22, 1954 3Sheets-Sheec 1 Patented Sept. 8, 1936 PATENT OFFICE STEERING MECHANISM Wilfred A. Eaton,

Bendix-Westinghouse Pittsburgh, Pa... assignor to Automotive Air Brake Company, Pittsburgh, Pa., a corporation of a Delaware Application June 22, 1934, Serial No. 731,986

12 Claims.

, anism which is especially adapted for use in con- 'nection with motor vehicles.

Another object of .the invention is to provide in a motor vehicle steering apparatus a novel con-. struction whereby the operator may readily steer motor vehicles of the larger type, such as trucks or busses, with a minimum amount of effort and atthe same time have complete control of the steering of such vehicles as heretofore.

Still another object is to provide a novel power steering mechanism for motor vehicles so constituted as to enable manual control of the steering operation to efiect a combined manual and power steering operation.

A further object is to provide in a mechanism' of the above character, a novel arrangement of parts whereby manually controlled power'operation of the steering apparatus will include a feel or reaction which will be reflected in the manually controlled. member in order to simulate as closely as possible the feel or resistance heretofore encountered during manual steering.

A still further object is to provide in a poweroperated steering mechanism for motor vehicles, a novel, simple and compact arrangement of parts so constituted as to be relatively'light in weight and capable of ready installation without the necessity of completely rebuilding manuallyoperated steering mechanisms now in common use.

The above and othernovel features of the invention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawings, wherein there are illustrated two embodiments of the invention. It is'to be expressly understood, however, that the drawings are for purposes of illustration only and are not designed as adefinition of the limits of the invention, reference being'had for this purpose to the appended claims.

In 'the drawings, wherein similar reference characters denote similar parts throughout the several views:

Fig. 1 is a side view, pa tly in section, of a power steering apparatus constructed in accordance with the present invention;

Fig. 2 is a transverse sectional view of the parts shown in Fig. 1;

Fig. 3 is a diagrammatic perspective view of the parts shown in Figs- 1 and 2; i

Fig. 4 is a perspective view of a modified form of the invention, and

Fig. 5 is a side view in section of the controlling levers shown in Fig. 4.

Referring more particularly to Figs. 1 and 2, the present invention is illustrated therein as including a manually-operable steering column or shaft 4, which is drlvably connectedby means hereinafter to be described to a rotatable steering shaft or member 5 having rigidly secured at one end thereof a pitman arm 6 which is adapted to be connected with a drag link and suitable steering connections, not shown, in order to steer the dirigible wheels of a motor vehicle.

Suitably secured to one end of the steering column 4 is a worm or cam i of well-known construction, with which there is adapted. to mesh a cam follower or gear member 8 rotatably carried as by means of bearings 9 by one-end of a lever ill, the other end of which is formed into a hub portion ii which surrounds but is spaced from a reduced end of the'steering shaft 5. As shown, the lever i0 is pivotally connected intermediate its ends to 2 one end of a lever I! by any suitable means such as pivot pin or bolt l3, and in order to insure free pivotal movement of lever ill with respect to the bolt iii, a. bushing it may be interposed therebetween. As viewed in Fig. 2, the left-hand portion ,of the bolt I3 is fixedly secured to the upper end of lever i2 as by means of drawing nut i5 tightly against the face of the lever.

In the form of the invention illustrated, the.

lever I2 is provided with a hub portion it which is suitably secured to the shaft 5 as by means of a key i1, it being apparent that rotation oflever l2 will thereby effect rotation of the steering shaft 5 and consequent operation of the steering mechanism operatively connected thereto. The lever I2 preferably extends below shaft 5, as viewed in Fig. 2, and the lower end portion is formed as a gear segment i8, see Fig. 1, with which a fluid motor is adapted to cooperate in order to provide power operation of the steering mechanism. Preferably, the mechanism above described is enclosed within a suitable casing 19.

In order to effect operation of the steering mechanism by power, there is provided a suitable power-actuating mechanism comprising opposed cylinders 20 and 2! having reciprocable pistons 22 and 23 therein, the said pistons being interconnected by a rack 24 in constant meshing engagement with the gear teeth of sector l8. Preferably, the power-actuatingmechanism is adapted 55 pressure although as well understood by those skilled in the art, any suitable fluid may be employed. As shown, air under pressure is conducted to the mechanism through pipes from a suitable air reservoir, not shown, the control of compressed air to the cylinders being effected by valve mechanisms 26 and 21 associated with cylinders 2| and 20 respectively. Referring to the valve mechanism 21, it will be observed that the same includes a casing 28 having intake and exhaust valves 29 and 30 secured together and re- 'ciprocatingly mounted therein, there being provided resilient means 3| for normally maintaining the valve-29 upon a seat 32 secured to the casing. The exhaust valve 30, as .shown, is normally spaced from its seat 33 formed in the head of a reciprocating piston member 34, this last-named member having a bore 35 formed therein which normally establishes communication between one side of the fluid motor and at atmosphere through duct 36 associated with the cylinder 20. Preferably, a spring 31 is interposed between the casing 28 and the piston 34 in order to maintain the latter in such a position that the bore 35 will not be closed by the valve 30. Thevalve mechanism 26 is constructed in a manner similar to the valve mechanism 21. y

In order to eifect operation of the valve mechanisms 26 and 21, the hub portion ll of the lever ID has rotatably mounted thereon a pair .of collars 38 and 39, the former being connected to the valve mechanism 26 by means of a rod 40, while the latter is adapted to actuate the valve mechanism 21 through rod 4|. a

In operation, manual rotation of shaft 4 and cam 1 will eflect operationof lever I 0 about pivot l3 by reason of the engagement of the cam follower 9 with the cam 1, such pivotal movement of the lever l 9 being limited by the spaced or lost motion connection between the hub portion ll of lever l0 and the reduced end of steering shaft 5. As viewed in Figs. 1 and 3, such operation of lever III will eflect movement of collar 39 and rod 4| to the right, for example, compressing spring 31 and effecting a closure of the bore 35 as soon as the seat 33 contacts with valve 30. Subsequent movement of the rod 4| to the right will serve to open the intake valve 29 against the tension of spring 3| in order to' permit air or other fluid under pressure to be conducted into the power cylinder 29 through-pipe '25 and duct 36,;whereupon the piston 22 and rack 24 will be moved to the right to eflect a counter-clockwise movement of the gear sector I8 and steering shaft 5 whereupon the dirigible wheels will be moved in the desired direction. It will be readily apparent that during the above-described movement of the gear sector I 9, the lower end portion of lever l0, together with the collars 39 and 39, will be moved to the left, as viewed in Figs. 1 and 3,

- by reason of the substantially self-locking nature spring 3| to close the intake valve 29 and upon continued movement of the collar 39 to the left, communication between the power cylinder 29 and atmosphere will be established through connections 36 and 35. It will also be observed that as soon as the above communication to the atmosphere has been established, the power cylinder 20 will become inoperative and no further movement of the steering mechanism will be effected by power.

Preferably, the springs 31 of the valve mechanisms are so constructed as to. readily yield during the usual operation of the steering mechanism in order to permit the functioning of the power apparatus. However, under certain circumstances it may be desirable to steer the vehicle manually, in the usual manner, and to permit the power apparatus to become operable only when a predetermined resistance to steering is encountered, such as for example, during travel in sandy or muddy roads, such an operation obviously conserving the supply of compressed air,

required to be carried by the vehicle. In such event it is only necessary to construct the springs 31 in such a manner that they will oppose the tendency of the valve operating rods 40 and 4| to compress them, during operation of the steering mechanism when only slight resistance to steering is encountered, but will yield as soon as a predetermined resistance is reached, thereby permitting operation of the power appara- It will be appreciated from the above that the construction or the parts is such as to enable a feel or resistance to steering to be reflected in the steering shaft 4 in order to convey to the,

operator the usual reaction to steering encountered during normal operation of steering gears of the manually-operated type, which reaction is highly desirable in steering mechanisms operated by power. For example, as soon as the lost,

motion existing between the hub portion ll of the lever l0 and the reduced end of shaft 6 has the actuation of the steering shaft 4 by the op- I erator to effect a movement of the upper end of lever II] to the left, as viewed in Fig. 1, the? operation of the valve mechanism will cause a reaction to be exerted which is conveyed to the operator through the steering shaft 4. 'Such an arrangement is extremely advantageous, as

will be appreciated, in that the usual resistance or reaction offered to steering may be readily" noted by the operator.

In the event that the operator wishes to steer the wheels of the vehicle in an opposite direction; the steering shaft 4 is moved in such a manner that the upper end of lever I!) will be moved to the right, as viewed in Figs. 1 and 3, thus ei'lecting operation of valve 26 to supply fluid under pressure through pipe connections 23 and 31 to the power cylinder 2| which will eil'ect a clockwise rotation of gear segment l8 and steering shaft 6 and upon a predetermined movement of the latter, will effect a discontinuance in the operation of the power cylinder in a manner similar to that above described in connection with power cylinder 20. It is to be pointed out that the construction is such that as soon as the lost motion between hub portion H of lever l9, and the reduced end of steering shaft 6 has been taken up and the selected power cylinder has been placed in operation, continued .rotation of the cam 1 will also add the manual eifort of the operator to the power operation of steering shaft 5 by reason of the abutting engagement between hub I i and shaft 5 effecting a connection between the cam follower 8, levers i and i2 and shaft 5.

Referring more particularly to Fig. 4, a slightly modified form of the invention is disclosed therein and includes a lever 42, one end thereof being cam operated by the steering column 4 while the other end is rotatably mounted on the vehicle frame in any suitable manner. Said last named end is also connected with a lever 43 which latter is associated with one end of a valve controlling lever 44 as by means of a link 45. As shown more particularly in Fig. 5, the valve controlling lever is provided with a hub'portion 46 surrounding but spaced from the end portion of the rotatable steering shaft 41, while the intermediate portion of said lever is pivotally connected, as by means'of a pivotpin or bolt 48, to a pitman arm or lever 49,0ne end of the latter being fixedly secured to the rotatable shaft 41. As shown in Fig. 4, the lower end of the pitman arm 49 is secured to a drag link and steering connections 56 of suitable design, it being un-, derstood that oscillating movement of arm49 in accordance with rotation of the steering shaft 41 will effect steering of the dirig'ible wheels of the vehicle through the steering connections 50" depending upon the direction of movement .of the steering column 4.

Means are provided for operating the steering shaft 41 by power, and preferably such power means are controlled by operation of the steering column 4. As shown, such means are constituted by power cylinders 50 and having pistons 52 and 53 respectively, which are interconnected by means of rods 54 and 55, the means for interconnecting such rods comprising a suitable coupling member 51 which is connected to the lower end of arm 58, the upper end of which is secured to the steering shaft 41. Any suitable source of fluid, such as air under pressure, is adapted to be conducted to the power cylinders by valve mechanisms 59 and 60, such valve mechanisms being similar in construction-to the valve mechanism 21 heretofore fully described in connection with that form of the invention illustrated in Figs. 1-3. As shown, the valve mechanisms 59 and 60 are provided with operating rods 6| andv 62 which are connected with a collar 63 rotatably mounted upon the hub portion 46 of lever 44. I

During operation of the above described modified form of the invention, considering the steering column'to be turned in such a direction as to effect a counterclockwise movement of link 43 with respect to the mounting thereof on the vehicle frame, it will be readily observed that link 45 will be moved to the right effecting a counterclockwise movement of lever 44 about its pivot 48, which latter, it will be appreciated, momen-' tarily remains stationary, since the same is connected through arm 49 to the dirigible wheels of the vehicle. Upon the counterclockwise movement of lever 44, it will be readily observed that the hub portion 46 of said lever, together with collar 63 rotatably m unted thereon, will be moved to the left, as vi wed in Fig. 4, taking up the lost motion existing between hub portion 46- and the'rotatable steering shaft 41, such movement effecting operation of the valve 59 to admit fluid under pressure to power cylinder 50 which will cause rod 54 to move to the right in order to effect power operation of the pitman arm 49 through lever 58 and rotatable shaft 41. It will also be readily observed that the valve mechanism 59 will be rendered inoperative by counterclockwise movement of lever 49 with shaft 41 by reason of the interconnection between the pitman arm 49 and the lever 44 at 48,- such connection effecting a movement of the hub portion 46 to the right, it being appreciated that the lower end of lever 44 secured to the link 45 will remain substantially stationary. In this form of the invention as in the previously described form, continued rotation of the cam 1 .by the operator will,

after .the lost motion between hub 46 and the steering shaft 41 has been taken up to operate the selected fluid cylinder, enable the manual effort of the operator to be added to the power operation of the steering mechanism. It is also to be understood that in this form of the invention the valve mechanisms 59 and 60 are of the fluid pressure reactive type similar to the valves 26 and21 and both of the valve mechanisms disin the steering operating linkage enables ready actuation of the valves controlling the flow of fluid under pressure to the power actuators and moreover provides a construction whereby the manual effort of the operator may readily supplement the power operation of the steering mechanism. The arrangement of these valves and of the power actuators, as above described, is also of such a nature as to enable a reaction or resistance to be exerted upon the manually-operable steering shaft which is readily noticeable'by the operator when rotating such shaft, to the end that the operator may more readily gauge the degree of steering as in steering mechanism of the manually-operable type.

While only two embodiments of the invention have been illustrated and described, it-is to be understood that the invention is not limited thereto but may be capable of being employed in other forms as well understood by those skilled in the art. 'Furthermore, the parts disclosed herein may be rearranged if desired, and certain of the parts maybe used without others without departing from the spirit of the invention. Reference.

a fluid motor operatively connected with one of said levers, and means dependent upon pivotal movement of one lever with respect. to the other lever for controlling the operation of said motor,

ond member, and means dependent upon pivotalmovement of said first member to take up said lost motion for controlling the operation of said motor. I Y

3. In a power steering mechanism for vehicles,

,a steering shaftl'a fluid motor for rotating said shaft, means including a manually operable steering column. for controlling the motor, and a mechanical connection between the steering shaft and the manually operable device comprising a pairof pivotally-connected members.

4. In a, power steering mechanism for vehicles, a steering shaft, a fluid motor for rotating said shaft, a manually operable device for controlling the motor, and a mechanical connection between the steeringshaft and the manually operable device comprising a pair of pivotally-connected members, one of said members being rigidly secured to said shaft, theother of said members having a part surrounding but spaced from said shaft.

5.-In a power steering mechanism for motor vehicles, a pair of angularly disposed shafts, a fluid motor for rotating one of said shafts, means for manually rotating the other of said shafts, a

, steering mechanism connected with the motordriven shaft, and means for controlling the =operation of said motor'comprising a member 'tosaid steering shaft, a second lever having a cam follower secured thereto at one end thereof adapted to cooperate with said cam, said second lever being connected to'a member having a hub portion surrounding but spaced from said steer- .ing shaft, means for pivotally connecting said first lever to said member between the ends '7. In a steering mechanism of the type having .a manually operable controlling member and a power-operated steering lever, the combination with said member, of means for controlling the power operation of said lever comprising an oscillatable lever having one end thereof connected with said member, means on said steering lever for pivotally mounting said oscillatable lever, and

means including a shaft associated with the other end of said oscillatable lever through a lostnio- .tion connection for limiting the oscillatable movement of the last named lever in either direction about its pivotal mounting.

8. In, combination with a manually rotatable shaft, a steering member, a fluid motor opera- 'tively connected with said steering member, valve mechanism for controlling said motor, and means for operatively connecting said shaft ancl memher and for controlling said valve mechanism to effect combined manual and power operation of said steering member comprising a lever operatively connected with said steering member, a motor-control lever plvotally mounted intermediate its ends to said flrst-named lever, one end of said motor-control lever being operatively connected with said manually rotatable shaft independently of said first named lever, means for connecting the opposite end of said control lever to said valve mechanism, and means for mounting said last-named end-for limited pivotal movement with respect to said first-named lever.

9. In a vehicle steering apparatus, having dirigible wheels for varying the direction of motion of a vehicle, a steering shaft, steering mechanism connecting the steering shaft with said wheels whereby rotation of the shaft moves the wheels ,to vary the direction of motion of the vehicle, a

fluid motor connected to the steering shaftand serving to rotate the same, a conduit for supplying fluid under pressure to said motor, a valve normally closing said conduit,- a steering wheel, means including a. lever fulcrumed intermediate its ends connected with said steering wheel and having one end surrounding said steering shaft, said end being operatively associated with said valve whereby rotation of said wheel moves said valve to open said conduit, and means directly connecting said fulcrum and said steering shaft whereby movement of the steering shaft in response to actuation thereof by said motor moves said fulcrum in a direction to close said valve.

10. In a power steering mechanism for motor vehicles, a manually-operable steering member, a power operated steering lever, a power device having a movable element connected with said steeringlever, and means for controlling said power device from said manually-operable steering member comprising a controlling lever fulcrumed intermediate its ends on said steering lever, a connection between said manually-operable steering member and one end of said controlling lever, and a member for mounting the other end of said controlling lever, said other end encircling said last namedmember but normally spaced therefrom to provide a lost motion connection, said power operated steering lever being secured adjacent one end thereof to said last'named member.

11. In a power steering mechanism for motor vehicles, a manually-operable steering member, a power operated steering lever, a power device having a movable element connected with said steering lever, and means for controlling said power device from said manually-operable steering member comprising a controlling lever fulcrumed intermediate its ends on said steering lever, a connection between said manually-operable steering member and one end of said controlling lever, and a member for mounting the other end of said controlling lever, said other end encircling said lastnamed member but normally spaced therefrom to provide a lost motion connection, said power operated steering lever being, mounted on said last named member.

12. In a power operated steering mechanism.

for motor vehicles, a manually-operable steering shaft, a rotatable' steering shaft, power means,

means for said power means; a levefoscillatably mounted on said arm for actuating said power controlling means, and means connecting said shaft aiid lever.

' WILFRED A. EATON. 

